In a treasure safe that keeps valuables such as bank notes and cash vouchers, devices for preventing theft by discouraging a break-in are implemented.
An example of a theft-prevention device is a device for causing a security alarm buzzer to go off when the treasure safe is opened improperly. However, this device is not very effective for preventing theft since the security alarm sound is unable to specify what is being stolen. Also, a battery is used as the power source for the alarm buzzer so that if the battery set to the device is dead, the alarm will not go off even when the treasure safe is opened improperly.
Another example of a theft-prevention device is a device that taints the notes with a special kind of ink so that they will be invalid as currency.
In Japanese Patent Laid-Open Publication No. 6-108741, a device including an ink tank, a spraying pipe, a thermal line, and a battery that are mounted in the device is disclosed. According to this prior art invention, when a treasure safe is opened improperly, electricity passes through the thermal line so that it generates heat. This in turn causes the spraying pipe to melt and thus, the ink spills out due to its own weight and taints the notes kept in the treasure safe. However, in this device, if the battery set in the device is dead, the thermal line will not generate heat and the ink will not come out even when the treasure safe is improperly opened.
In Japanese Patent Laid-Open Publication No. 4-98387, a device including an ink bag and an oscillation rod implementing a needle is disclosed, wherein the ink bag is mounted under a top board of the treasure safe and the oscillation rod is placed under the ink bag. According to this prior art invention, the oscillation rod is supported by a spring that applies a force to this oscillation rod so that when the treasure safe is improperly opened, the oscillation rod is moved by means of the spring force. As a result, the needle makes a hole in the ink bag, causing the ink to spill out due to its own weight and taint the notes kept in the treasure safe. In this device, the life of a battery is not a problem because a battery is not used. However, since the ink spills out only from its own weight, the ink cannot be sprayed with much force. Thereby, the notes will not be severely tainted and there may even be notes that have not been marked by the ink.
Also, neither the device disclosed in Japanese Patent Laid-Open Publication No. 4-98387, nor the device disclosed in Japanese Patent Laid-Open Publication No. 6-108741, is arranged into a module structure. Therefore, the assembling of the treasure safe becomes complicated and the size of the treasure safe has to be made larger.